The invention relates to a headlamp cleaning unit for the front area of a motor vehicle. A headlamp wiper is arranged on a driven shaft which is mounted in a housing in an axially fixed manner. The longitudinal axis of the shaft runs approximately parallel to the longitudinal axis of the vehicle, and one end face of the shaft, at the front side of the vehicle, projects beyond the drive housing.
Such headlamp cleaning units are generally known (also see Bosch-kraftfahrtechnisches Handbuch, 20th edition, VDI Verlag, Dusseldorf, 1987). If the motor vehicle strikes an obstacle even at a low speed (for example at most 4 km per hour), the shaft can be thrust to the rear by the force acting axially on its end face, which can damage the drive housing. If the wiper shaft is fixed to the headlamp itself, the headlamp will also be damaged.
In a passenger car having swing-in headlamps, it is also known (EP-B 0, 097,365) to arrange the headlamp cleaning unit rigidly on each headlamp so that is can be swung in and out together with the headlamps. Consequently, although the shaft driving the wiper is movable relative to the front area of the vehicle, it is still rigidly arranged on the headlamp itself.
The object of the invention is to provide a headlamp cleaning unit of the above-mentioned type, in which damage to the wiper drive caused by the shaft in the event of a front collision at low speed is avoided.
This object is achieved according to the invention in which a locking device which axially fixes the shaft is designed to release the shaft for axial movement if an axial load occurs which exceeds a predetermined value. With the shaft no longer axially fixed with respect to such an axial load on its end face projecting to the front, it can be displaced to the rear so that the drive housing and other elements of the wiper drive or of the headlamps cannot be damaged.
In a preferred embodiment of the invention, the locking device is elastically deformable- It is thereby possible, for example after an impact, to return the shaft from its axially displaced position into its operating position in which the locking device axially fixes the shaft again.
In another preferred embodiment of the invention, a cap is arranged on the rear (in the direction of the load) end of the shaft projecting out of the housing, which cap is held by means of catch lugs in corresponding catch locations of a rear opening of the housing- This cap serves the dual purposes of axially fixing the shaft in the housing, and transmitting the cleaning water to the headlamp unit.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.